Air handlers may be used to regulate and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. To this end, an air handler may include an inlet, an outlet, and a fan. In some examples, the air handler may also include a filter. The filter may be designed to remove particles (e.g., dust) from air that flows through the air handler. Air flowing through the filter is resisted as it is forced through the filter. The resistance that the filter provides to air flow may depend on the type and design of the filter. The resistance may also depend on the cleanliness of the filter. For example, an old filter may exert a higher resistance compared to a new filter because the old filter will likely have accumulated particles that function to clog the filter and resist air flow.